Known threaded pipejoints, which are employed in particular in the oil industry and especially in oil wells, have tapered or cylindrical threads as well as at least one stop integral with one of the members in order to restrict the thread make-up at the time of the assembly of the two members.
The idea is equally well known of effecting the assembly of such joints by applying a torque which lies within a zone of predetermined values, the torque being applied by a device which enables it to be measured.
Prior mehods have not entirely given satisfaction because it may occur that by reason, for example, of the presence of a foreign body such as a chip of metal in the lubricant on the threads, or in consequence of a seizure at the level of the threads, the predetermined maximum torque is reached as a result of abnormally high resistance to make-up and without the surfaces of the stop for restriction of the threading, coming correctly into contact with one another. The result is defective tightening of the joint because under this assumption the sealing surfaces are in general not in contact or are in contact only in an unsatisfactory way.
A general object of the present invention is to provide a new method and apparatus which enable these disadvantages to be eliminated in a simple manner and at low cost.